It frequently is necessary to transfer information from one integrated circuit (IC) package to another. To do this, output signals on different pins of one of the integrated circuit packages must be connected to inputs through leads or pins on the other of the integrated circuit packages. When various clock signals, data signals and command signals need to be communicated from one integrated circuit to another, limitations on the number of dedicated pins or leads on each of the integrated circuit packages frequently are reached. One solution is to increase the size of the package and the number of pin interconnections from the package to the integrated circuit located therein. Since integrated circuit packages, however, typically are sold in configurations having pre-established numbers of pins on them, any requirement which uses large numbers of these pins for transferring information from one package to another necessarily limits the number of input and output connections which can be made to others of the pins. When the package size must be increased to handle larger numbers of pins, costs for both the integrated circuit package and systems with which the package is used are increased.
Efforts have been made in the past to utilize what is known as "packetized" data streams to cause a transmitting IC and a receiving IC to be synchronized with one another. When this is done, the data stream packets then may be assigned specific functions within every given time frame cycle. For example, one part of the data stream may be reserved for address information, whereas another part is reserved for data information. All of the signals, however, travel on the same lead for such a packetized data stream. For such systems to operate, it is necessary to provide accurate synchronization between the operations of the transmitting IC and the receiving IC, since the arrival of information within any given packet or time frame position is what establishes whether the information is of a particular type, such as the address and data information discussed above.
Many applications exist for communication protocols between integrated circuit packages or devices for communicating different command signals or states, prior to the transmission of data related to the particular command states. For example, applications exist in electronic ovens having different command states for "on", "off", "load" (with a specific temperature), and for "start" and "stop" times, with transmission of the necessary time information. If separate leads or pins are required for interconnecting transmitting ICs and receiving ICs for all of these functions, the number of pins required, simply to accommodate the command functions, easily can become excessive.
Accordingly, it is desirable to provide a communication protocol for integrated circuits (ICs) which uses a reduced number of pins to control the different command states without using packetized data streams.